What makes london dispersion forces stronger

Jun 1, Related questions What are molecular dipoles? When do dipoles occur in a molecule? How can I identify dipoles in molecules? The strength of London dispersion forces depends on the size of the molecule or atom. Larger atoms and molecules have more electrons. This leads to larger dipoles being established. London dispersion forces increase the larger the atomic size.

Molecules with a permanent dipole are polar. Polar molecules display attractions between the oppositely charged ends of the molecules. The strength of these interactions within a given molecule depends directly on how easily the electrons in the molecules can move i. Large molecules in which the electrons are far from the nucleus are relatively easy to polarize and therefore possess greater dispersion. Figure 1: Dispersion Interaction with an instantaneous dipole on one He atom inducing a dipole on a nearby He atom.

If it were not for dispersion forces, the noble gases would not liquefy at any temperature since no other intermolecular force exists between the noble gas atoms.

The low temperature at which the noble gases liquefy is to some extent indicative of the magnitude of dispersion forces between the atoms. Electron distribution around an atom or molecule can be distorted. This distortion is called the polarizability. Figure 2: Dispersion interaction in the gas phase. It is possible that these forces arise from the fluctuating dipole of one molecule inducing an opposing dipole in the other molecule, giving an electrical attraction.

Key Points London dispersion forces are weak intermolecular forces and are considered van der Waals forces. Temporary dipoles can occur in non-polar molecules when the electrons that constantly orbit the nucleus occupy a similar location by chance. Temporary dipoles can induce a dipole in neighboring molecules, initiating an attraction called a London dispersion force.

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